29 April 2017

A Long Banded Silverline takes nectar from the flower of the Mile-A-Minute Weed

In this 10th instalment of Butterflies' Nectaring Plants series, we feature a rather invasive 'weed', the Mile-A-Minute Weed (Mikania micrantha). This plant is a native to Central and South America, and is a fast-growing vine that was intentionally introduced to a number of countries. In recent years, it has become an unwanted invasive plant that has been a target of biological control in some countries.

The Mile-A-Minute Weed is a member of the Asteraceae (Compositae) family that is native to tropical Central and South America with a climate and humidity that is similar to Singapore and Southeast Asia. It is able to grow vigourously via its climbing vines and can spread rapidly, if unchecked, often smothering other plants in its way. Young shoots of this plant have been reported to grow at an average of 25mm to 80mm per day!

The Mile-A-Minute Weed climbs on other plants and often smothers them completely!

If supported, the plant can climb up trees to as high as 25m, completely covering the supporting plant and eventually depriving the host of sunlight and nutrients, and even eventually killing it. The plant can grow in a variety of habitats but usually prefers damp, lowland clearings or open areas, where there is adequate temperate, light and rainfall. It also grows along streams and roadsides, along edges of forests and forest plantations, along fence-lines, in pastures and wastelands and on and among trees and shrubs. It may be common in areas affected by slash and burn agriculture.

A female Colour Sergeant feeds on the flowers of the Mile-A-Minute Weed

In Singapore, it can be found in open wastelands, recently-cleared sites, coastal reclaimed sand-filled sites and even at the fringes of our nature reserves. Aesthetically, the Mile-A-Minute is not a particularly pretty plant and is not usually used intentionally as part of any landscaping designers' palette of plants. However, some landscape contractors are experimenting with this plant as part of their vertical greenery walls, exploiting the Mile-A-Minute's propensity for climbing large distances vertically.

The slender stem of the Mile-A-Minute Weed bears opposite leaves at about 5-20cm intervals. The dark green leaves are ovate with a cordate base. The leaves have pointed tips and a heart-shaped base, and generally triangular in shape. The foliar margins are curvy, undulate and irregular. Mature leaves are thicker than the younger leaves and smooth to the touch. The foliar venation is net/pinnate.

The white flowers on branched inflorescence of the Mile-A-Minute Weed

Flowers are in compact heads of 4-6 mm long, small and white to greenish and usually hanging on much branched inflorescence. Fruits are 2 mm long achenes, black with a head of white pappus hairs 2-3 mm long. The featherlike seeds are dispersed by wind. A single stalk can produce between 20 and 40 thousand seeds a season.

The small white flowers of the Mile-A-Minute Weed are attractive to butterflies. It is interesting to see that small and large butterflies feeding on the flowers. Although we can only speculate at this point in time, that the quantity of nectar is sufficient to satiate the appetites of both the large and small butterflies alike. Although I have not come across any photos of the Papilionidae feeding on the flowers of this plant, I have observed a Common Mormon fluttering around the flowers before.

Various Nymphalidae butterflies feeding on the flowers of the Mile-A-Minute Weed

The larger Danainae - the Crows of the genus Euploea in particular, have been seen to feed on the flowers of the Mile-A-Minute Weed. Amongst the other Nymphalidae, the larger species like the Cruiser, Malay Lacewing, Autumn Leaf, Great Eggfly, Tawny Coster and various Sergeants (Athyma spp) have been observed feeding on the flowers of this plant - usually within the forested areas of our nature reserves, where the plant can be found climbing on other plants.

Examples of Pieridae on the Mile-A-Minute flowers

The Pieridae, in particular the Grass Yellows of the genus Eurema and even the Tree Yellow have been seen on the flowers of the Mile-A-Minute Weed. It is highly likely that other species of the Pieridae will also take to the flowers of this plant.

A variety of Hairstreaks and Blues on the Mile-A-Minute Weed's flowers

The Lycaenidae has also been often seen on the flowers of this plant, often feeding on the flowers and moving from flower to flower for long periods of time. Various Theclinae have been photographed at the flowers of the Mile-A-Minute Weed in urban parks and gardens where the weed grows wild on fences and other shrubs/trees. Amongst butterfly species that are seen are the Copper Flash, Long Banded Silverline, Club Silverline and various Blues from the Nacaduba genus.

The Hesperiidae are also often seen to feed at the flowers of the Mile-A-Minute Weed throughout the day. Thus far, we have not seen the larger Skippers on the flower of this plant, although many smaller species like the Lesser Dart and other species of the Potanthus, Oriens and Ampittia genera have been regularly observed at the flowers of this plant.

Although this weed is a bane to landscape managers and contractors, where they have to often physically remove the plants before they smother and kill off other more valuable plants, the Mile-A-Minute's flowers are a good source of nectar for our butterflies. Hence even an unwanted invasive is still useful to our butterflies and should be judiciously managed and not totally be eradicated from our botanical biodiversity in Singapore.

The next time you are out on a walk in our parks or forests, do look out for flowering bushes of the Mile-A-Minute Weed and search for the hungry butterflies feeding on their flowers.

22 April 2017

In our blog article on the the review of the year 2016, we referred to some seven new additions to the Singapore Checklist, bringing the total number of butterfly species observed in Singapore to 331. This weekend's article features four of these species and offers some insights on the status of these species in Singapore. Very often, we have migratory species that make their occasional appearance in Singapore and due to their seasonality, these are classified as 'seasonal migrants' in the Singapore Checklist.

However, there are still some lookalikes that are hard to distinguish, except perhaps with physical voucher specimens or even using DNA barcoding to establish a distinct species that occurs in our environment. Then there is always the possibility that some species have eluded observation by hiding deep in Singapore's forested nature reserves. They are probably rare, but resident species, yet to be discovered or re-discovered.

Amongst one of the surprising finds last year, was the Dark Jungle Glory (Thaumantis noureddin noureddin). A relatively pristine individual was found by NIE lecturer Assistant Prof James Lambert on the premises of the Nanyang Technological University. The butterfly was found dead with its wings spread open.

The Dark Jungle Glory is described as being dark brown on the upperside with the wing bases a shining purple-blue, with a fascia of diffuse white spots on the forewing. The dark-greyish brown underside has a white post-discal line which is shaded with dark brown and a number of ocelli on the hindwing. The species is often found in bamboo thickets and fly close to the ground in dark heavily shaded habitats.

A Dark Jungle Glory in its typical habitat amongst dead leaf litter on the forest floor

It is curious that this species, considered a re-discovery is still found in Singapore after all these years. We do not believe that this is a seasonal migrant, as the Dark Jungle Glory stays in shaded habitats close to its likely caterpillar host plant of bamboos. It is probably rare, but has remained extant in Singapore in very limited habitats. It should be looked for in future, particularly in the NTU area which still has pockets of undisturbed heavily shaded forested areas.

The next large species that has been observed in Singapore over the past years, is the Dark Blue Tiger (Tirumala septentrionis septentrionis). This butterfly, which resembles the Glassy Tigers of the Danainae subfamily, has been observed from time to time, and it was not until a confirmed shot by Chung Cheong was recorded recently. It was probably missed due to its resemblance to the Glassy Tigers and proved elusive.

A Dark Blue Tiger shot in Singapore in 2006

The Danainae have been known to be strong flyers and display migratory tendencies. That the Dark Blue Tiger has been sighted several times in Singapore, is therefore not surprising, as the tough "Tiger" can survive rough conditions that would have been fatal to other more delicate species. The species is not uncommon in Malaysia, and is often seen in butterfly enclosures where it is one of the farmed species for display. The Dark Blue Tiger is a large butterfly with narrow elliptical bluish markings. It resembles other species in the Parantica and Ideopsis genus but it appears much bluer in flight.

A Ganda Dart with the hindwing patch with the veins not darkened

The next two species to be discussed are skippers from the Hesperiidae family. It is often challenging to identify skippers from field shots - particularly amongst the lookalike species, of which several species can be very similar in appearance. Amongst these are the species from the genus Potanthus and Telicota. These orange-black skippers are small, skittish and appear frustratingly identical to butterfly watchers.

The species referred to as the Ganda Dart (Potanthus ganda). This species is of the same size and appearance as the more commonly found Lesser Dart (Potanthus omaha). However, the Ganda Dart prefers the forested areas in the nature reserves in Singapore whilst the Lesser Dart is more widespread and can be found in urban parks and gardens.

The Ganda Dart differs from the Lesser Dart in that the veins on the yellow band on the hindwing above are not blackened. It is also described to have deeper orange colouring (but a rather unreliable characteristic when comparing weathered individuals with pristine ones). Both the Ganda Dart and Lesser Dart flies with the usual skittish skipper habits and often stop with their wings opened in the typical skipper fashion. Photos of the Ganda Dart appeared online as early as 2010 but was not validated until recently, with breeding records.

The next skipper of interest is the rare species from the genus Zographetus. These are forest-dependent butterflies and are rarely, if ever, found outside the sanctuary of the nature reserves in Singapore. Three species have been listed as extant in Singapore by the early authors. However, only one - Zographetus doxus (Spotted Flitter) has been recorded with certainty.

A Rusty Flitter perches in the shaded understorey in the nature reserves

Over the years, another closely related species, the Rusty Flitter (Zographetus ogygia) has been photographed but not included in the Singapore Checklist due to the uncertainty relating to their superficial features. However, as more and more evidence appeared, the confidence level of distinguishing these two species has risen and therefore the 2nd species Zographetus ogygia has been added to the Singapore Checklist. A 3rd species, Zographetus rama, recorded previously in Singapore, should be looked for.

It is highly likely that there continues to be discoveries or re-discoveries in our Singapore's forests where rare species have eluded observation till now. Many of these species may be cryptic in appearance, with several species looking very similar to each other. The skippers, in particular, the brown ones, tend to be difficult to identify from a single field shot and specimens may need to be collected to establish the ID of the species with greater certainty.

Note : The English Common Name of Zographetus ogygia follows the Butterflies of Thailand 2nd Edition by Pisuth Ek-Amnuay. Elsewhere it is known by other common names but we will accept the Southeast Asian name as "Rusty Flitter".

15 April 2017

A quarter of 2017 had come and gone. The fourth month of the year seems quiet enough, although the uncomfortable tension that came with two US military strikes on Syria and Afghanistan lingers in the air. It would appear that the Trump administration will not hesitate to show its destructive force in the use of (currently) conventional weapons in sending a strong message to ISIS.

Already, the amassing of US military hardware in South Korea, and the reciprocal response from China is causing consternation in north-east Asia. Will the US, which appears to be emboldened by their military strikes on the ISIS strongholds, also use force to teach North Korea a lesson? Will North Korea stay quiet in the face of US hostilities, as Syria and Afghanistan appear to be? We live in times of great uncertainty indeed.

I was in China waiting for my flight to take off, when news of the US strike on Afghanistan broke. Although far away, the impact of the incident caused quite a bit of delays at airports in China. Despite no one mentioning that the 'temporary closure' of certain airports in China and the flight delays that ensued were a result of the international incident, we can only speculate that China was on high alert during that short period of time.

And then there was the United Airlines incident that buzzed the internet for a few days. Due to the prevailing policy that airlines in the US are allowed to over-sell their flights, whenever a flight is full, the airline will invite passengers to forego their seats (for a little compensation) to accommodate the airline's policy. However, the incident on United Express Flight 3411 where a "booked, paid and seated" passenger was selected at random and physically dragged out of the plane by security personnel.

I recall that some years ago, I was offered to take a later flight when the plane that I was booked on, was full. The American Eagle counter staff was polite and persuasive and I agreed to take a US$150 compensation and took a flight that was 3 hours later. The difference was that I was persuaded not to take the flight before I boarded the plane. The current incident where a passenger was violently dragged off the plane after being seated is totally unacceptable, which is probably why it set off an internet storm all around the world.

Perhaps living the life of a butterfly is a lot less complicated? This month, we feature a small hairstreak or Lycaenidae species called the Silver Forget-Me-Not (Catochrysops panormus exiguus). It was re-discovered in Singapore back in 1997. References indicated that this species was not seen in Singapore since the late 19th century and was therefore considered 'extinct'. However, a small population was observed in the Khatib Bongsu area and Pulau Ubin. Subsequent sightings of this species on Sentosa and various parts of the island indicated that the species is extant and resident in Singapore.

Considered a moderately rare species, the Silver Forget-Me-Not is usually encountered singly where it flies with a rapid erratic flight amongst the low shrubbery. The caterpillar host plant is Pueraria phaseoloides which is a "weed" growing in open wastelands and cleared areas.

Comparison between the Silver Forget-Me-Not and the Forget-Me-Not showing the position of the costal spot on the forewing edge on the underside of the forewing.

This species is not to be confused with its lookalike cousin, the Forget-Me-Not (Catochrysops strabo strabo). Almost identical in most respects, these two species are hard to separate in the field, as they frequent the same habitats and display the same habits. The key distinguishing difference is the location costal spot on the underside of the forewing.

Upperside of the male and female Silver Forget-Me-Not

The Silver Forget-Me-Not is pale shining blue on the upperside of the male. The female is heavily black dusted with broad black apical area on the forewing, and dull blue wing bases. The underside is greyish white with the usual Lycaenidae streaks and spots. The hindwing has a long filamentous white-tipped tail at vein 2.

Puddling Silver Forget-Me-Nots

At certain times of the day, both males and females of the Silver Forget-Me-Not can be observed to open their wings partially to sunbathe. These are the only times when one can observe the uppersides of the wings, as they normally stop with their wings folded shut, even when they feed on flowers or when they puddle on damp footpaths and streambanks.

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